1. Field of the invention
The invention concerns a device for treatment by hyperthermia, allowing to heat a diseased area of a patient through dissipation of an electrical energy applied according to an electrical field through use of unipolar electrodes disposed adjacent to the diseased area or within said area. The invention is of particular interest in that it allows to considerably reduce the effects traumatizing for the patient, produced by using such treatments.
2. Summary of the prior art
Hyperthermia is a known process, which consists in heating living biological tissues to temperatures substantially higher than their normal temperature, and which is utilized in the treatment of various illnesses and especially in cancerotherapy. In the example of this latter application, it is desirable to heat the tissues to be treated to temperatures of about 44.degree. C. to 45.degree. C., while avoiding, as much as possible any substantially increase in temperature of the healthy surrounding tissues.
This condition raises a problem which resides in the correct localization of the heated area. In certain configurations which the diseased tissues can present, this correct localization of the heating is impossible to obtain with electrodes situated outside the patient's body. Therefore, in numerous cases, treatment by hyperthermia is carried out through using electrodes directly implanted in or around the area to be treated, so as to more closely confine the heated area.
Such probes can be either of the bipolar or the unipolar type. In the case of bipolar probes, the high frequency electric energy supplied by a generator, in the form of a voltage, can be applied to a single probe of this type, to heat the area in which it is implanted. In the case of unipolar probes, the high or average frequency voltage supplied by the generator is applied to two separate unipolar probes, each of these two probes being connected to one of the output poles of the generator, the heated zone being thus mainly established between two unipolar probes of the type that can be implanted.
The implantation of a bipolar or unipolar probe in a diseased area represents for a patient an operation that can be accompanied by acute pain, and which is particularly traumatizing for treatments by hyperthermia for a given zone to be treated, must generally be repeated at variable frequencies and over periods of time comprised between several days and several tens of days.
It is to be noted that furthermore during treatment, certain tissues of the area to be treated can undergo different rises in temperature, this being able to lead during treatment to modifying the implantation of the probes. Therefore, one of the objects of the invention is to allow to modify the configuration of the heated area, without requiring that the implantation of the probes be modified.